Add heartbeat check for stomp

Related to https://github.com/DiamondLightSource/blueapi/issues/1082

- I04's bluesky-stomp occassionally disconnects for no obvious reason, causing GDA to hang when it tries to run plans. After the disconnect, BlueAPI successfully sees the POST request, but doesn't follow it up with a PUT request, so the plan never starts.

- Even if stomp manages to automatically reconnect, the PUT requests still aren't being triggered by the POST. Deleting the BlueAPI environment seems to be the only way to fix this

- The error isn't very obvious to scientists since it's a generic timeout. I think BlueAPI should have a heartbeat check against stomp and flag a more obvious error if it can't connect